Socket for bayonet base lamp or the like



June 1, 1943. v w, L N L 2,320,627

SOCKET FOR BAYONET BASE LAMP 0R THE LIKE Filed June 25, 1941 mm IN 25 cf/z e/z/ar- Patented June 1, 1943 UNITED TENT OFFICE SOCKET FOR BAYONET BASE LAMP OR THE LIKE 2 Claims.

My invention relates to sockets for bayonet base lamps or fittings and has reference more particularly to a construction thereof which insures greater certainty of positive electrical connections.

Bayonet base lamps and fittings are commonly used in low voltage electrical systems of automobiles and the like, the bayonet base serving to detachably mount the lamp Or fitting and also to provide electrical connection of the lamp or other device in the electrical system. Such systems are usually of the single wire ty-pe wherein a ground connection with metal parts of the automobile is utilized for the return side of the circuit, and my invention is especially advantageous in connection with such single wire systems although it is not necessarily limited thereto.

The bayonet base of the lamp or fitting commonly employed in such systems consists of an extension surrounded by a cylindrical metal sheath from the opposite side of which project two short diametrically aligned pins for securing the base in a socket, and at the outer end of the extension is a central contact, insulated from the metal sheath, and serving with the latter to provide separate electrical connections through which current is supplied to the lamp or fitting.

The socket commonly employed for such bayonet base lamps or fittings comprises a cylindrical, thin walled metal sleeve in which the bayonet base is telescopically inserted, and this sleeve is provided with diametrically opposed longitudinal slots extending inwardly from th outer end to accommodate the diametrical pins of the base, said slots being formed at their inner'ends with corresponding circumferential offsets or extensions so that when the base is fully inserted in the socket a slight turning of the base in the socket engages the pins in the circumferential ofisets.

As commonly constructed, the sockets above described have a coil spring in the bottom supporting a round disk of insulating material which is freely slidable longitudinally in the socket and positioned so that when the bayonet base is inserted in the socket the base engages the disk and compresses the spring, and when the base is fully inserted and turned in the socket to engage the diametrical pins of the base with the circumferential offsets at the inner ends of the longitudinal slots of the socket, the spring tension, acting through the insulating disk against the inner end of the bayonet base, holds the diametrical pins of the bayonet base against the margins of the circumferential offsets which are suitable formed so that the spring tension retains the pins in the offsets and thus locks the base in the inserted position in the socket.

The insulating disk of the socket has a central contact on its outer face with which the central contact of the bayonet base engages when the latter is inserted in the socket and this central contact of the insulating disk has a conductor connected therewith which extends outwardly through the spring and inner end of the socket and is connected to the supply terminal of a source of electrical energy so as to supply current to the bayonet base lamp or fitting through the two central contacts which are maintained in electrical engagement by the socket spring. The return to the source of electrical energy for completing the circuit is through the socket, which is usually grounded to a metal part of the automobile, which metal part in turn is connected to the return terminal of the source of electrical energy, and the bayonet base lam-p or fitting is electrically connected with the socket through the diametrical pins of the bayonet base which are maintained in electrical engagement with the socket by the spring in the bottom of the socket acting through the insulating disk against the inner end of the bayonet base. Thus this spring serves the double purpose of maintaining electrical contact at the two points where the current enters and leaves the bulb or fitting, namely at the two central contacts and at the places where the diametrical pins engage the circumferential offsets of the socket slots.

Socket failure usually manifests itself in the form of poor or broken electrical contact at eimaintaining proper electrical engagement of the insulator disk contact with the central contact of the bayonet base or of the bayonet base pins with the socket.

Such socket failure is largely avoidable by using rust proof metals but because of the greater cost of such metals it is common practice to use cheaper metals which are not sufiiciently rust resistant to give, with present socket designs, satisfactory socket life under severe servicecondi tions to which they are often subjected, especially in motor trucks.

The principal objects of my invention are to provide an improved socket for bayonet base lamps and fittings; to avoid the detrimental effects of rust and grit and interference thereof with satisfactory operation of'the socket; to fa cilitate inserting of the bayonet base in the socket; to avoid slotting of the exposed end of the socket; and in general to provide a socket for bayonet base lamps and the like which is of simple construction and more convenient and serviceable than those now available, these and other objects being accomplished as pointed out hereinafter and as shown in the accompanying drawing, in which Fig, l is a perspective view of a socket constructed in accordance with my invention and having a lamp bulb mounted therein;

Fig. 2 is a central longitudinal sectional view of the socket of Fig. 1 with the lamp bulb mounted therein and shown in elevation;

Fig. 3 is a cross sectional view of the socket taken on the line 33 of Fig. 2;

Figs. 4, 5 and 6 are side views of the socket showing modified forms of pin engaging openings; and

Figs. 7, 8, 9, and 10 are cross sectional views of fragmentary portions of the socket side wall showing other forms thereof for interlocking engagement with the bayonet base pins.

Referring to the drawing, and particularly to Figs. 1, 2 and 3 thereof, the reference numeral I indicates a conventional bayonet base lamp which has the usual mounting extension or base surrounded by the cylindrical metal sheath II and central contact I2 at the outer end insulated from the metal sheath I, the latter of which has the two pins I3 extending diametrically outward therefrom at opposite sides and which serve to secure the lamp in the socket.

The socket, which is indicated as a whole at I4, is of conventional form in the respect that the inner end is formed with an annular seat I5 for a spring I6 which supports an insulating disk H which has a central metal contact I8 on its outer face connected to a conductor I9 which extends outwardly through the spring I9 and an opening 29 at the inner end of the socket I4.

Heretofore the sockets of these bayonet base lamps have been of cylindrical or circular form corresponding to that of the lamp base and provided with bayonet type slots or grooves at opposite sides extending inwardly from the outer end to receive the pins I3. In my present construction, however, no such slots or grooves are required, the socket M being of non-cylindrical or non-circular form, preferably square in cross section as shown, having corners 2| to accommo date the pins I3 as the lamp base is inserted in the socket, and at a suitable distance from the outer end of the socket the side walls 'of the socket are formed with openings or offsets into which the pins I3 may be swung from the corners 2| by a turning movement of the lamp, to interlock with the side Walls and lock the lamp in the socket.

These openings or offsets may be variously formed, for example openings such as shown at 22 in. Figs. 1, 2 and 3 may be employed which are preferably elongated lengthwise of the socket and each has the left hand edge 23, thereof as you face the respective socket side wall, located approximately at the longitudinal central line of the respective socket side wall but slightly to the left thereof. The opposite side edge 24 of each opening 22 is sufiiciently close to a socket corner 2I so that the lamp base pin I3 may be turned freely from the corner 2| into the adjacent opening 22 or from the opening hack into the corner and the lower ends of these-openings 22 are preferably rounded as shown. The outer end of each opening 22 is cut slightly diagonal to the edges 23 and 24 to provide an edge 25, the portion of which nearest the edge 23 is slightly nearer the outer end of the socket than the portion thereof nearest the edge 24.

In mounting the lamp in this socket M the lamp base is turned so that the pins I3 thereof are in line with any two opposite corners 2| of the socket and in this position the lamp base is inserted in the socket and in the inserting operation the contact I2 on the lamp base engages the contact I8 of the disk I! and forces the latter toward the inner end of the socket thereby compressing the spring Ifi. After the pins I3 pass below the outer edges 25 of the socket openings 22 the lamp is then, turned in a clockwise direction and the pins thus enter a pair of opposed openings 22. Turning of the lamp is continued until the pins I3 strike the edges 23 of the openings into which they have been turned and then upon release of the lamp the spring I6 forces the lamp base outwardly until the pins I3 engage the outer edges 25 of the openings. Because of the diagonal arrangement of these edges 25 the pins I3 will seat and be held by the spring in the corners between the edges 23 and 25 and remain securely in place therein until the lamp base is pressed inwardly against the tension of the spring I6 and turned counterclockwise to return the pins I3 to socket corners 2| whereupon the lamp may be withdrawn from the socket.

With this square form of socket, the cylindrical base I I of the lamp and likewise the round disk I! can contact with the socket walls only along the longitudinal center lines thereof and by reason of this limitation of contact area, frictional resistance to free movement of the lamp base and disk lengthwise of the socket is reduced to a minimum and such free movement is unlikely to be interfered with by any rust or grit that may accumulate between the socket and lamp base. Thus, notwithstanding any accumulation of rust or grit, the tension of the spring I5 is fully available to hold the contact I8 firmly against the contact I2 and at the same time to hold the pins I3 firmly against the outer edges 25 of the openings 22 and a good positive electrical connection at these places is assured at all times.

Because of the corners 2| that are provided to accommodate the pins I3, no slots are required at the outer end of the socket and moreover, greater convenience is afforded in inserting the lamp in the socket as there are four quarter turn positions in which it may be inserted whereas in previous sockets it could be inserted onlyin either of two half turn positions.

Furthermore, other forms of openings 22 or facilities for engaging the pins I3 may be employed. The outer edge of the opening 22 may be perpendicular to the edges 23 and 24 of the opening as shown at 26 in Fig. 4 with a notch 21 next to the edge 23 to receive the pin I3 or a round opening 28 as shown in Fig. 5 may be employed centrally located in the socket side wall or an opening such as shown at 29 in Fig. 6 may be employed, likewise centrally located in the socket.

Furthermore, instead of punching out the material at the openings 22 it may be slit along lines corresponding to the edges 23 and 25 and bent outwardly as indicated at 30 in Fig. 7 to accommodate the pins [3 or a portion of each side wall of the socket may be merely offset outwardly as indicated at 3| in Fig. 8, without cutting slitting, to provide a recess or cavity 32 at the inner side of each wall to accommodate the pins I3 and it will be understood thatpin engaging facilities similar to those of Figs. 5 and 6 may also be formed as indicated in Figs. 9 and 10 in the same manner as the pin engaging facilities of Figs. 7 and 8, of which Figs. 9 and 10 are illustrations.

While I have shown and described the present,

invention in its preferred forms, it is understood that various changes and modifications may be made therein without departing from the principles of the invention, the scope of which is to be determined by the appended claims.

What I claim is:

1. A square socket for reception therein of the bayonet base of a bayonet base lamp or the like, said socket having each of the surrounding sides thereof spaced from the opposite side to tangentially engage the bayonet base therebetween and having internal corners between adjoining sides constituting guideways to slidably accommodate a bayonet pin of the bayonet base, each side having a seat facing toward the inner end of the socket and enterable laterally from an adjoining corner whereby a bayonet pin may enter therein from said corner, and an electrical contact in the bottom of the socket and resiliently depressible by an inserted bayonet base to resiliently lock the bayonet pin thereof in said seat.

2. A square socket for reception therein of the bayonet base of a bayonet base lamp or the like, said socket having each of the surrounding sides thereof spaced from the opposite side to tangentially engage the bayonet base therebetween and having internal corners between adjoining sides constituting guideways to slidably accommodate a bayonet pin of the bayonet base, each side having a bayonet pin engaging notch facing toward the inner end of the socket and enterable laterally from an adjoining corner whereby a bayonet pin may enter therein from said corner, and an electrical contact in the bottom of the socket and resiliently depressible by an inserted bayonet base to resiliently lock the bayonet pin thereof in said notch.

WALTER E. LU'NDELL. 

